Conventionally, cement-based materials (i.e. concrete and the like) having excellent mechanical properties (i.e. compressive strength, bending strength and the like) have been developed.
For example, in the “Claims” of Japanese Patent Publication No. 59182/1985, a hydraulic composite material which includes “inorganic solid particles A” having a diameter of 50 Å to 0.5 μm (for example, silica dust particles), “solid particles B” having a diameter which is 0.5 to 100 μm and which is larger than that of “particles A” at least by one order (for example, particles including at least 20 weight % of portland cement), a surface-activating dispersant (for example, a concrete superplasticizer such as a highly condensed naphthalene sulfonic acid/formaldehyde condensate), and an “additional material C” (for example, at least one selected from the group consisting of sand, stone, metallic fibers and the like).
The hydraulic composite material described in this gazette has compressive strength of at least 100 MPa after hardening and has excellent mechanical properties (see Table 1 in the sixty-third column in page 32 of the gazette).
Generally, a cement composition (for example, concrete and the like) having excellent mechanical properties (i.e. compressive strength, bending strength and the like) as described in the above-mentioned gazette has the following advantages.
(a) When a building or the like is constructed by using the cement composition having excellent mechanical properties in a method of cast-in-place, concrete layers can be thin. Thus the reduction of the amount of concrete, the saving of labor, the cost reduction, the increase of available space and the like can be achieved.
(b) When a precast member is produced by using the cement composition having excellent mechanical properties, the precast member can be thin. Thus the weight reduction, the easiness of transportation and construction, and the like can be achieved.
(c) Wear resistance, durability against neutralization or creeping, and the like can be improved.
The hydraulic composite material described in the above-mentioned Japanese Patent Publication No. 59182/1985 can be preferably used in view of the advantages (a)-(c).
However, it is further desired that a self-filling property is achieved in addition to the properties of the hydraulic composite material described in the above-mentioned gazette.
Namely, when a building or the like is constructed in a method of cast-in-place, or when a precast member is produced, it is advantageous that a hydraulic composite material having excellent fluidity and material separation resistance (namely, a hydraulic composite material having a self-filling property) is used in view of the reduction of the time required for casting a hydraulic composition such as concrete and the like, and the reduction of the time required for applying vibration to the concrete or the like after casting.
On this point, it is difficult to improve both the properties before hardening such as fluidity and material separation resistance, and the mechanical properties after hardening such as compressive strength, bending strength and the like simultaneously with regard to the hydraulic composite material disclosed in the above-mentioned Japanese Patent Publication No. 59182/1985. For example, when compressive strength over 130 MPa is desired, or when fibers are blended for improving bending strength, the ratio of water/binding material must be no larger than 0.20. Thus the fluidity lowers, and a self-filling property cannot be achieved. On the other hand, when a self-filling property is attempted to be obtained, the ratio of water/binding material, and the amount of a water reducing agent increase so greatly that it is difficult to express compressive strength over 130 MPa.